add tutorial 2

Basic-App/kv/buttons.kv

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+<AddButton>:
+    text: "+1"
+    font_size: 50
+
+<SubtractButton>:
+    text: "-1"
+    font_size: 50

Basic-App/main.kv

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+<Container>:
+    display: display
+    rows: 1
+    BoxLayout:
+        orientation: "vertical"
+        AddButton:
+            on_release: root.add_one()
+        SubtractButton:
+            on_release: root.subtract_one()
+    Label:
+        id: display
+        font_size: dp(50)
+        text: '0'

Basic-App/main.py

@@ -0,0 +1,43 @@
+from kivy.app import App
+from kivy.lang import Builder
+from kivy.uix.button import Button
+from kivy.properties import ObjectProperty
+from kivy.uix.gridlayout import GridLayout
+
+
+from os import listdir
+kv_path = './kv/'
+for kv in listdir(kv_path):
+    Builder.load_file(kv_path+kv)
+
+
+class AddButton(Button):
+    pass
+
+
+class SubtractButton(Button):
+    pass
+
+
+class Container(GridLayout):
+    display = ObjectProperty()
+
+    def add_one(self):
+        value = int(self.display.text)
+        self.display.text = str(value+1)
+
+    def subtract_one(self):
+        value = int(self.display.text)
+        self.display.text = str(value-1)
+
+
+class MainApp(App):
+
+    def build(self):
+        self.title = 'Awesome app!!!'
+        return Container()
+
+
+if __name__ == "__main__":
+    app = MainApp()
+    app.run()